Huge (sometimes exhausting) learning experience for sure!

Look at areas where pipes come into the house and crawl spaces, etc.

During our inspection revealed the need for a re-pipe and 200 amp panel. 

Not real good:1) They may just sink molys (you hope) in sheetrock and while TVs are getting lighter, mount needs to go into a stud2) Had one deal where they hit a water pipe in the wall - Hilarity did not ensue3) Who patches it when they take down the TV and move?

Now we plan on going to move to Florida on the chance that we wont have to deal with frozen pipes.

That more than likely will be a big deal...and like you said, the stink pipe issue becomes huge...especially if you have a large opening in the wall right behind the new sink location, with no side wall in sight. 

Would a new exhaust system, for example, be depreciated rather than expensed in that tax year?

You do not want deteriorated OR incorrect type of pipe and all fittings, crushed flex connectors, cross-threaded connections, etc.

Lots of interior plumbing that we did ourselves (frozen burst pipes).  2 Kitchens, 2 baths, some electrical, Rugs  Garage partions,  work and it cost approx $40,000.  

The subject property is a condo in a desirable costal market that was damaged due to a pipe bursting in one of the walls.